The WAP is a protocol definition which allows subscriber terminals of a mobile communications system to use services implemented on the Internet or in a corporate intranet. Further information about WAP is available in the home pages of the WAP Forum, which defines the WAP specifications, at http://www.wapforum.org.
In WAP the Hypertext Markup Language HTML typically used in WWW services (World Wide Web) to describe the contents structure and outer appearance of hypertext is replaced by WML (Wireless Markup Language).
WAP services do not employ similar search keys, such as “share” (of the stock market), as those to which users are accustomed in the value added short message services of the GSM (Global System for Mobile Communications) environment. The network part of a mobile communications system employing the WAP typically comprises a WAP Gateway which is used to identify a service request coming from a subscriber terminal and to transfer the request to the Contents Server that provides the service requested. The WAP Gateway then transmits the response data generated by the contents server on the basis of the service request to the subscriber terminal.
Since WAP services are not based on a unique search key, but a service is requested using its Internet address (Uniform Resource Locator, URL), the generating of billing data for the service is problematic. In principle, billing may be based on three different elements, depending on how the system is implemented.
If the bi-directional data transmission connection between the subscriber terminal and the mobile communications system is implemented using circuit-switched data transfer, such as a data call, then it is natural to apply connection time charging in the billing. However, a problem in this is that the billed amount is difficult to divide among the different services used. In addition, this does not allow an individual service to be charged for on the basis of its contents.
The data transmission can also be executed on a packet-switched connection, using the short message service or GPRS (General Packet Radio Service), for example, in which case billing can naturally be carried out on the basis of the number of packets transferred.
However, there are many services for which, due to their nature, transaction-based billing is the most reasonable both for the user of the service and its provider. Transaction in this context means a single service event. For example, if the service concerned is the current stock exchange quotation of a share, it is subject to a fixed, service transaction-based price not dependent on the connection time or the number of packets transferred.
In a mobile communications system which employs a wireless application protocol and packet-switched data transfer, for example, and in which a service is identified on the basis of its Internet address, transaction-based billing is difficult to implement because Internet addresses are complex in their structure and therefore the monitoring of traffic in the WAP gateway and in the associated billing system is problematic.